This invention relates generally to pen-based computing systems, and more particularly to associating captured digital data with a writing surface.
Printed systems exist that provide an absolute and relative reference for a device scanning a surface. One such system uses dot-enabled paper including an encoded dot pattern that can be imaged by a scanning device, such as a smart pen. The scanning device scans a portion of the dot pattern and determines the location of the scanned portion relative to the rest of the dot-enabled paper using the dot pattern. The ability to determine location of the scanning device is important for many applications, such as electronic capture of written notes made by a user on the dot-enabled paper.
A notebook may contain multiple pages of dot-enabled paper, each page having a different dot pattern. In such a notebook, the scanning device is able to scan a portion of the dot pattern on a page in the notebook and determine both the identity of the particular page (e.g., the page number) and the location of the portion of the dot pattern within the page. The dot pattern is often generated by an algorithm that is capable of producing only a finite number of unique dot patterns spread over a certain area or a certain number of pages. The number of unique dot patterns may be limited for other reasons, such as limitations in the scanning device or in the production or distribution of the dot-enabled paper.
As a result, it is often necessary to produce multiple instances of dot-enabled paper having the same dot pattern. For example, multiple copies of a notebook may be produced where a particular page of one notebook has the same dot pattern as the corresponding page of another notebook. For example, the tenth page in multiple notebooks is encoded with the same dot pattern. In this situation, the scanning device will be unable to distinguish between two notebooks, and notes taken on two corresponding pages of the two notebooks will be assumed to be in the same position by the scanning device. Therefore, even though the user most likely intends for the notes on the two pages to remain separate, they will be combined when stored by the scanning device and when later accessed by the user.
It is also possible to describe a function, such as a calculator, associated with a region of a page having a particular dot pattern. This function is activated by applying the scanning device to the region of the page. However, if the scanning device is applied to a region of another page with the same dot pattern, the function will still be activated whether or not the user intended to activate the function.
Since every page of dot-enabled paper cannot have a unique dot pattern for the reasons discussed above, there is a need to reuse the same dot pattern for new notes or functions. Accordingly, a system and method is needed to enable electronic capture of written data from multiple copies of dot-enabled paper having the same dot pattern that avoids ambiguities and unwanted combining of captured written data while minimizing the burden placed on the user.